Al-Qaida is taking advantage of Pakistan's political turmoil to ramp up operations in the tribal belt and possibly plot fresh terrorist attacks abroad, western and Pakistani officials warn. As President Pervez Musharraf battles to retain power, violence is surging in Waziristan, where Osama bin Laden's senior henchmen have taken shelter behind a corps of Taliban fighters.

"They have humiliated the army and made things very difficult for a president who is already in trouble. It's a very clever strategy," said a western military official. The UK and US fear that a "catastrophic" terrorist attack could be launched from Waziristan, he added.

Waziristan's place as a hub of al-Qaida operations was highlighted recently when police in Germany arrested three men - two Germans and a Turk - accused of plotting to attack a US military base in the country. German officials said they had travelled to Waziristan for explosives training.

The July 7 London transport bomber Muhammad Siddique Khan is also believed to have trained in Waziristan.

However, efforts to catch or kill the al-Qaida commanders believed to be behind such attacks are being frustrated by a wave of daring attacks by the militants aimed at the heart of the Pakistani military. In the past three weeks suicide bombers have killed 17 American-trained commandos at a high security base, and 25 civilians, many of whom were employed by the ISI military intelligence agency, in an attack on a bus in Rawalpindi. Pakistani officials blame Waziristan-based militants for both attacks.

In Waziristan locals also found the bodies of two murdered men, one of whom was dumped inside a coffin with his throat slit. A note accused him of being a US spy.

The army meanwhile continues to negotiate for the freedom of 213 soldiers who were kidnapped in South Waziristan a month ago.

The fighting is led by the Pakistan Taliban - a loosely linked network of tribal militias with ideological or historical ties to al-Qaida. Ironically, one of the most influential leaders is a former CIA client. In the 1980s US intelligence funnelled weapons and money to Jalaluddin Haqqani, a fiercely conservative commander along the Afghan border. Today his eldest son, Sirajuddin, known as "khalifa" to his followers, is a key al-Qaida ally.

"They are the great facilitators in all this," said the western official. "They are into everything in North Waziristan - guns, drugs, cross-border activity. You name it, Haqqani is behind it."

The chaos has enabled a small core of hardened al-Qaida operatives to move freely in Waziristan, experts say. "Their numbers have not increased, but their freedom of movement has. They have an assurance they are relatively safe, that the Pakistanis will not be able to get them," said the western official.

"The government doesn't understand that this is the tip of the iceberg," said a former head of security for the tribal areas, retired Brigadier Mehmood Shah. "Behind all this is al-Qaida, solidifying their position. They have declared war on Pakistan. Now the army must make a war plan."

The chaos is fuelling violence in Afghanistan. The number of cross-border attacks originating in Waziristan this year has already surpassed the 2006 total, according to the western military official. A senior Nato commander told a recent visitor that the alliance controlled "at best" 20% of southern Afghanistan.

But the west's greatest worry remains the attacks that Waziristan-based operatives may be plotting in the US or Europe. Senior figures believed to be in Waziristan include Abu Laith al-Libbi, who tried to overthrow the Libyan leader Colonel Muammar Gadafy in the early 1990s and who later escaped from a jail in Saudi Arabia.

The US military blamed him for orchestrating a suicide bombing outside Bagram airbase during a visit by to Afghanistan by the US vice-president, Dick Cheney, last May.

Other senior Bin Laden loyalists include Abu Yahya al-Libbi, a Sunni ideologue who escaped detention in Bagram and now frequently appears in al-Qaida videos, and Adam Gadahn, a California native nicknamed "Azzam the American".

It may also be home to Bin Laden, who last week called on Pakistanis to rise and topple Gen Musharraf.

The remote area has become a one-stop shop for aspiring terrorists, said Seth Jones of the Rand Corporation, a Washington-based thinktank. "You can learn how to make an IED [improvised explosive device], how to elude detection from western intelligence agencies, get funding or receive ideological support. Then you go off and do it."

Senior officials from Whitehall and Washington have flown to Islamabad in recent weeks to discuss the problem, including the US undersecretary of state John Negroponte. But Gen Musharraf is unlikely to take stern action soon - his re-election hinges partly on support from an Islamist party with links to the Taliban.

For some the spiralling violence demonstrates Gen Musharraf's importance to the fight against al-Qaida; others say it is a sign that his sell-by date has expired. "We expect a lot more trouble if he remains in power. His very presence is increasing militancy," said a veteran journalist, Rahimullah Yusufzai, in Peshawar.

An army spokesman, Major General Waheed Arshad, said it was "ridiculous" to link Gen Musharraf's political plight to the military situation in Waziristan. "Everyone knows there's a chain of command," he said.

But he insisted that the president remained in full control. "He's aware of the situation and he remains involved at all times," he said.